monorepo eslint config

.eslintrc.cjs

/**
 * Create a set of default eslint configs for a typescript project
 * @param {string} dir
 * @returns
 */
const tsProject = (dir) => ({
  plugins: ["@typescript-eslint", "import", "node"],
  parser: "@typescript-eslint/parser",
  parserOptions: {
    tsconfigRootDir: __dirname,
    project: [`${dir}/tsconfig.json`],
  },
  settings: {
    "import/parsers": {
      "@typescript-eslint/parser": [".ts", ".tsx"],
    },
    "import/resolver": {
      typescript: {
        alwaysTryTypes: true,
        project: [`${dir}/tsconfig.json`],
      },
    },
  },
  extends: [
    "eslint:recommended",
    "plugin:@typescript-eslint/recommended",
    "plugin:@typescript-eslint/recommended-requiring-type-checking",
    "prettier",
  ],
  rules: {
    // False positives. There be dragons here. Most common culprits are
    // optional chaining and nullish coalesce.
    // Using it causes typescript-eslint to believe it is
    // of type "any" and trigger these eslint errors.
    // https://github.com/typescript-eslint/typescript-eslint/issues/2728
    // https://github.com/typescript-eslint/typescript-eslint/issues/4912
    "@typescript-eslint/no-unsafe-argument": "off",
    "@typescript-eslint/no-unsafe-assignment": "off",
    "@typescript-eslint/no-unsafe-call": "off",
    "@typescript-eslint/no-unsafe-member-access": "off",
    "@typescript-eslint/no-unsafe-return": "off",
    "@typescript-eslint/restrict-template-expressions": "off",

    // https://typescript-eslint.io/rules/no-unused-vars/
    // https://eslint.org/docs/rules/no-unused-vars
    "no-unused-vars": "off",
    "@typescript-eslint/no-unused-vars": [
      "error",
      { ignoreRestSiblings: true },
    ],
  },
});

/**
 * Get a list of all lintable files in a directory
 * @param {string} dir
 * @returns
 */
const lintableFiles = (dir) => [
  `${dir}/**/*.+(t|j)s?(x)`,
  `${dir}/**/*.+(c|m)js`,
];

/** A set of import rules that ensure files are imported in a way webpack and vscode understand */
const nextJsImportRules = {
  "import/extensions": ["error", "never", { json: "always", css: "always" }],
  "node/file-extension-in-import": [
    "error",
    "never",
    { ".json": "always", ".css": "always" },
  ],
  "node/no-missing-import": "off",
};

module.exports = {
  root: true,
  rules: {},
  // baseline js parsing options set env for CJS files and skip known builds
  env: {
    es6: true,
    es2018: true,
    node: true,
  },
  ignorePatterns: ["**/build/*", "**/.swc/*", "**/.next/*"],

  // migration prep for eslint 9
  overrides: [
    // check yourself before you wreck yourself
    {
      files: ["**/.eslintrc.cjs", ".lintstagedrc.cjs", "commitlint.config.js"],
      extends: ["eslint:recommended", "prettier"],
    },

    // api
    {
      files: lintableFiles("./services/api"),
      excludedFiles: ["**/__generated__/*", "**.d.ts"],
      ...tsProject("./services/api"),
      extends: [
        ...tsProject("./services/api").extends,
        "next/core-web-vitals",
      ],
      settings: {
        ...tsProject("./services/api").settings,
        next: {
          rootDir: "services/api/",
        },
      },
      rules: {
        ...tsProject("./services/api").rules,
        ...nextJsImportRules,
      },
    },

    // site
    {
      files: lintableFiles("./services/site"),
      excludedFiles: ["**/__generated__/*", "**.d.ts"],
      ...tsProject("./services/site"),
      extends: [
        ...tsProject("./services/site").extends,
        "next/core-web-vitals",
      ],
      settings: {
        ...tsProject("./services/site").settings,
        next: {
          rootDir: "services/site/",
        },
      },
      rules: {
        ...tsProject("./services/site").rules,
        ...nextJsImportRules,
      },
    },

    // worker
    {
      files: lintableFiles("./services/worker"),
      excludedFiles: ["**/__generated__/*", "**/*.d.ts"],
      ...tsProject("./services/worker"),
      rules: {
        ...tsProject("./services/worker").rules,
        "no-restricted-imports": [
          "error",
          {
            patterns: ["src/*"],
          },
        ],
        "node/file-extension-in-import": ["error", "always"],
      },
    },
  ],
};